Part of our “Mastering Manual Mode” series.
Listen to the focal length episode here:
The focal length is one of the fundamental aspects of photography. It is how we describe lenses, and it’s how we change perspective without moving our feet. Changing your focal length will have a dramatic change in your final image.
What is the focal length?
The focal length is a calculation of an optimal distance from the point where the light rays converge to form a sharp image to the digital sensor or film at the focal plane of the camera.
The focal length of a lens is determined with the lens focused at infinity. The millimeters that we use to describe a lens, describes the focal length, not the physical dimensions of the lens itself.
What does focal length tell us?
First of all, it tells us the field of view and angle of view or put simply, how much of the scene is captured on the sensor. We generally refer to this is a wide-angle (zoomed out), or telephoto (zoomed in).
Secondly, it tells us the magnification or how large the individual elements will be captured on the sensor. So, the longer the focal length, the narrower the field of view, and the higher the magnification. The inverse is true for shorter focal lengths. Short focal lengths will have a wider field of view and lower magnification.
Check out the bottom of the cheat sheet.
Types of Lenses
There are two types of lenses, zooms, and primes. Zoom lenses have a variable focal length. You’ll see this noted on a lens like this: 18mm-55mm. This means that the focal length of this lens can be adjusted “zoomed” between 18mm and 55mm, as well as all focal lengths in between. Prime lenses, however, have a fixed focal length. This means they cannot be adjusted. They will only have one focal length listed, such as 50mm.
Zoom Benefits
Zoom lenses are more versatile. They offer a range of focal lengths, so you don’t have to move. This means you can get a variety of shots without changing lenses or moving around. When shooting horses, this means you’ll get less dust on your sensor because you do not have to change lenses so often. If you shoot subjects that are moving, but you cannot move, then zoom lenses will let you get more images that are framed how you want. Zoom lenses are what most camera companies use as kit lenses.
Prime Benefits
Prime lenses are typically lighter weight and more compact because they only cover one focal length. They also tend to have a larger maximum aperture (smaller number). Example, 85mm f/1.2 or the 200mm f/2 compared to the 70mm-200mm f/2.8. Although this seems like a small difference on paper, it is a massive change in the final image. Because of this larger aperture, you can shoot pictures with a faster shutter speed, shoot in even lower light, have a blurrier background (shallow depth of field), and prime lenses typically have the better quality glass. Since there are fewer moving parts, the manufacturers make fewer compromises in image quality.
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Lens Classifications
Fisheye
Fisheye lenses see a large angle of view, around 180 degrees. These lenses are typically shorter than 10mm.
Ultra-Wide
Ultra Wide Angle lenses are in the 10-14mm range. Some cell phone cameras are here. If you want to capture nearly everything, this is where you’ll want to be. Images that are close to the camera will appear much more significant than those further away. You can use this to your benefit, or it can make features of humans and animals look very strange. You can accentuate small things by putting them very close to the lens.
Wide
Wide Angle lenses have a focal length between 14-35mm. The effects are similar to the ultra-wide with less distortion, and the difference between subjects close the lens and further from it is less dramatic. If you’re shooting landscapes, large groups, confined spaces, or you want to do some forced perspective photography, these are the lenses you’ll go to first.
Standard
As we move to longer focal lengths, the next step is the Standard Lenses. These are in the 50-60mm range. These lenses appear to have a similar field of view and compression as the human eye. These lenses have minimal distortion compared to their wider siblings. You’ll grab lenses in this range for things like nature and possibly portraits. Be careful using these for portraits; they can still make parts of your subject that are closer to the lens be slightly larger than those further away. You can reduce this effect by stepping back and reducing the relative distance. If you’re shooting on a crop sensor body, this will force you to step back anyway, so the effect is hardly noticeable. We will get into the sensor size in a future episode of the podcast.
Telephoto
Telephoto lenses are the most common in equine photography. These lenses are in the 70-200mm range. This range is so common that many manufacturers will make zoom lenses that cover the whole range. You’ll see offerings from Canon, Sigma, Sony, Nikon, and others that are 70-200mm or 80-200mm. These focal lengths lend themselves well to shooting so many things from portraits, to products, to barrel racing, team roping, rodeo, and so many more. My 70-200mm lenses have made more money than all the other lenses combined (I have a lot of lenses, so that’s saying something). This focal length has noticeable compression. You’ll see the objects behind your subject appear closer than they actually are. People’s and horse’s features will look natural and correct. As you get closer to 200mm, it can be effortless to get a shallow depth of field (blurry background) even at smaller apertures as long as your background is far enough way.
Super-Telephoto
Super Telephoto lenses are my personal favorite. These lenses are 300-600mm or more. I shoot with my 300mm 2.8 as much as I can because I love the way it looks. These lenses are great for wildlife, sports, portraits, or anytime where the subject is pretty far from you. I’m usually shooting barrel races from 168-420mm, for example. I do this so for my safety and to not interfere with the contestants. You don’t want to be the person who ruined someone’s chance at big money or, worse, gets someone hurt because of your actions. Super Telephoto lenses help you stay well out of the way while still getting the shot you want.
Macro
Macro lenses actually fit in the categories above, but they have the unique ability to focus on subjects that are very close to the lens. Some common macro lenses are 60mm, 100mm, 200mm. A lens is truly a macro lens if it can reproduce images on a 1:1 scale. This means that 1 inch in real life is 1 inch on your sensor. The most comment example is insects and flowers but, if you shoot a picture of some leatherwork, for example, a macro lens would be able to capture that detail.
Teleconverters
Teleconverters (extenders) are useful to alter the focal length of some lenses. They typically only work on telephoto lenses. Teleconverters mount between your camera and lens. The most common teleconverters are 1.4x and 2x. They multiply the focal length by 1.4 or 2, respectively. So, if you have a 200mm lens and you put a 2x teleconverter on it, then you have a 400mm lens. However, the drawback is that you lose two stops of light with a 2x teleconverter and one-stop of light with a 1.4x teleconverter. Each “stop of light” is twice as much light. Put another way, if you put a 1.4x teleconverter on a 70-200mm f/2.8 lens you now have a 98-280mm f/4 lens. If you are shooting with strobes or you have the sun, then that’s probably not a big deal. However, if you’re shooting in low light, that might not be acceptable. Teleconverters are an inexpensive way to get a long focal length but the image quality and maximum aperture can suffer. Pretty much everything in photography is a compromise, but that’s part of the fun, right?
Sensor Size
We will deep dive into sensor size in a later episode. However, the size of your sensor makes a huge difference in how a focal length looks in your final image. There are “full-frame” sensors that are approximately the size of 35mm film. “Crop” sensor cameras, aka APS-C sensors, are much smaller and have a similar effect as a teleconverter. They literally “crop” into an image by 1.4x or 1.6x (depending on the manufacturer) in relation to a full-frame equivalent. There are smaller sensors like in an iPhone or “medium format” sensors that are much larger than a full-frame sensor. This paragraph doesn’t really do the sensor size topic justice. This is just an overview.
Summary
The focal length is measured in millimeters (mm) and describes the field of view and magnification of a lens. There are zoom lenses and prime lenses. Zoom lenses are more versatile but have a smaller max aperture and other compromises in image quality. Prime lenses are fixed focal lengths but offer fewer compromises in image quality. Prime lenses generally have a larger maximum aperture (smaller f/stop). Lens classifications are fisheye, ultra-wide, wide, standard, telephoto, and super-telephoto. Macro lenses can reproduce images on a 1:1 scale, which is super close-up. If you need a “longer” lens, try using teleconverters but beware of the drawbacks.
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